More Inductive Pickup

[Brendan Simon]

> I was told that an inductive pickup (from a timing light) will
> produce enough current to flash an LED.  I have not tried this yet,
> however, I am wondering if the pulse width from a spark is long
> enough to "see".  What is an "average" length of a spark?
> 

I found that the voltage was enough to light a LED most of the time.  
I used a wave shaping circuit (AM radio detector like) and then through
a opto-coupler.  This worked for some motorbikes and not others.  Something
to do with lower compression I think.

Anyway, the led isolation didn't really work for me; not direct from the
pickup.  I really think there needs to be some kind of high impedence buffer
amp to isolate the effect of pickup/cable on the rest of the detection circuit.

Then the signal could be shaped, fed through a comparitor with hysteresis, and
maybe even through a monostable.

Brendan Simon
brendan at rdt.monash.edu.au